Judge circles round support beam (7)
I believe the answer is:
radiate
'beam' is the definition.
(I know that beam can be written as radiate)
'judge circles round support' is the wordplay.
'judge' becomes 'rate' (rating is a kind of judging).
'circles' indicates putting letters inside.
'round' is a reversal indicator.
'support' becomes 'aid' (to aid is to help or support).
'aid' in reverse letter order is 'dia'.
'rate' enclosing 'dia' is 'RADIATE'.
(Other definitions for radiate that I've seen before include "Disseminate" , "Emit (rays or waves)" , "Spread outwards" , "Emit rays; diverge" , "Travel from centre in all directions" .)